Answer:
a) 晩 -> 勉 -> 加 -> 吸
晩 BAN - evening, night
勉 BEN - effort, hard work
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
吸 KYUU, su(u) - suck, inhale, smoke
b) 早 -> 古 -> 員 -> 財
早 SOU, SA, haya(i) , haya(meru) - early, fast, hasten
古 KO, furu(i) - old
員 IN - member
財 ZAI, SAI - money, wealth, property